1. Field of the Invention
Embodiments of the invention generally relate to method and apparatus for electrochemical mechanical planarization and chemical mechanical planarization. More specifically, embodiments of the present invention relate to carrier heads used in planarization.
2. Description of the Related Art
Presently a carrier ring is coupled to a carrier head, of a polishing assembly of an electrochemical mechanical planarization (ECMP) or a chemical mechanical planarization (CMP) apparatus, and circumferentially surrounds a retaining ring. The retaining ring circumferentially surrounds a substrate and retains the substrate within an inner diameter of the retaining ring, and provides edge processing control. The carrier ring and retaining ring are both configured to contact a polishing surface of the ECMP or CMP apparatus during polishing. The carrier ring provides relative positioning of referencing of the carrier head to the polishing surface. The carrier ring laterally contacts the retaining ring with an inside surface of the carrier ring, at a lower portion of an outside surface of the retaining ring during processing of the substrate and provides lateral referencing of the retaining ring.
Because carrier ring/retaining ring interaction area is close to the substrate processing area, the carrier ring/retaining ring interaction may affect processing of the substrate. The interaction causes undesirable defects in the substrate. The defects can be caused in a number of ways, some of which include uneven wear on the retaining ring and vibrations between the carrier ring and retaining ring. The defects can further affect the service life of all the components of the apparatus.
Therefore, a need exists to establish a new carrier ring/retaining ring interaction while eliminating the direct surface to surface contact between the carrier ring and retaining ring near the substrate processing area.